Manufacture of alkali-metal amides



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T EWAN MANUFACTURE OF ALKALI METAL Ammas Filed March 51 1924III/11111111 'IIIIIIIIIIA Jan. 19 1926.

Patented Jan. 19, 1926.

UNITED STATES A 1,570,467 PATENT OFFICE.

THOMAS EWAN, OF GLASGOW, SCOTLAND.

ICANUI'ACTURE' OF ALKALI-HE'IAL AMIDES.

Application filed Iaroh 31, 1924. Serial No. 708,104.

the following is a specification.

similar to that describe This invention relates to themanufacture ofalkali metal amides and will be described with reference to themanufacture of sodamide by way of example though it is also applicableto the manufacture of other amides.

It is known that solutions of sodium in anhydrous liquid ammonia slowlyform sodamide with liberation of hydrogen but the reaction isexceedingly slow. Platinum accelerates the reaction catalytically.

It is the object of my invention to provide means for obtaining sodamideand other amides by a novel process. Another object is to rovide amethod of obtaining amides rapid y and directly at a low temperature.Another object is to produce amides from the amalgams of the corresonding metal. Further objects are to provi e new methods of acceleratingthe reaction between alkali metals and liquid anhydrous ammonia.

The sco e of the invention will be defined in t eclaims. The process maybe carried out in various ways, of which the following are examples.

Figures 1 and 2 of the drawings illustrate suitable apparatusdiagrammatically.

E'wample 1.

In Fig. 1 an electrol. ic cell 1 is used, in my co-pending applicationSerial No. 703,102 and worked in the same wa with the exceptionsdescribed below. he electrolyte is a solution of parts by weight ofsodium cyanide in 100 parts by weight of liquid anhydrous ammoma. Theamalgam contains 0.05% of sodium. The collecting and separating vesselsare omitted. The cathode 19, provided with the lead 20 is constructed ofan active catalyst, e. g., high-carbon steel and the ebonite linin isomitted, thus exposing the sodium solutlon to the catalytic action ofthe metal 'of the containing vessel 2 (e. g., steel). Additionalcatalytic surfaces 3 may be arranged near the surface of the electrolyte4 so that they are in contact both with sodium solution and withelectrolyte. The amalgam fiows in at the pipe 21 and out at the pipe 22forming a layer 23 which acts as anode and contacts with the lead 24:. Apipe 5 is provided through which the electrolyte overflows into filter 6without affecting the level of the electrolyte in the cell 1. The.sodium produced is rapidly converted into sodium amide which is almostinsoluble in the sodium cyanide solution and therefore crystallizes outas a white mud. The suspended mud is continuously swept out of the cellby feeding in fresh sodium cyanide solution from the reservoir 7. Whenfilter 6 is filled the flow is diverted to a duplicate filter (notshown). The liquid is expelled (by raising the pressure in 6 in anyconvenient wa through filter plate .8 (which may be 0 fine wire gauze)into receiver 7 The cake of sodamide is then washed free from adheringsalt solution by admitting liquid ammonia through valve 9. The washingsare transferred to vessel 7. If the quantity of ammonia used inwashingexceeds that consumed in the formation of the amide and carried awayWith the hydrogen at 11 the excess must be removed'b evaporation. Thewashed amide is finally eated a little above its melting point (about150 C.) and run off through valve 10 into moulds.

Example 2.

A sodium solution is made by electrolysis as described in my co-pendingapplications Serial Nos. 703102 and703103, or metallic sodium made. byany known method is dissolved in liquid anhydrous ammonia. So-

dium cyanide 1s added to the solution which is placed in a steel vesselat 17 C. to 30 C. under pressure. Additional catalytic surfaces may beused. A suitable apparatus is indicated-in Fig. 2 of the drawings.

Solid sodium is placed in vessel 12 through door 13, a solution of asodium cyanide in liquid anhydrous ammonia is placed in vessel 14(suitable quantities are 1 art sodium; 3 parts sodium cyanide an a 10parts ammonia but these may vary within wide limits; it is desirablethat after mixing two liquid layers should be formed). The cyanidesolution is run by pipe 15 into vessel 12. The sodium dissolves to asolution which floats on the cyanide solution, both being in contactwith the steel walls used instead of solid sodium, the excess ammoniaintroduced must be evaporated off (by heating vessel 14 for example)before the next charge is introduced.

Example 3.

A solution of sodium in liquid anhydrous.

- ammonia is run into a vessel such as vessel 12, Fig. 2, in which highcarbon steel is used as catalyst without the addition of a salt. It isconverted into amide more slowly than in presence of the salt; the amidemay be recovered as described in examples 1 and 2 except that no washingis required.

I prefer to use solid catalyst but I find that the finely dividedmercury (produced when a solution of mercuric cyanide is added to thesolution of sodium in ammonia) also exerts a catalytic activity.

I declare that what I claim is 1. The process of manufacturing alkalimetal amide which comprises passing an electric current between an anodeof alkali metal amalgam and a cathode immersed in a solution of inertalkali metal salt in liquid anhydrous ammonia and catalyzing thereaction between the ammonia and the metal thus removed to yield theamide.

E2. The process of manufacturing an alkali metal amide which comprisesbringing a solution of the alkali metal in liquid anhydrous ammoniacontaining a dissolved inert salt into contact with a catalyst capableof accelerating the reaction between the alkali metal and the ammonia.

3. The process of converting an alkali metal into its amide whichcomprises producing a solution of the alkali metal in liquid anhydrousammonia containing a dissolved inert salt in such amount that two liquidlayers are formed and simultaneously bringing both layers into contactwith a solid catalyst capable of accelerating the reaction between thealkali metal and the ammonia.

4E. The process of manufacturing an alkali metal amide which comprisesbringing a solution of the metal in liquid anhydrous ammonia intocontact with high carbon steel.

5. The process of manufacturing alkali metal amide which comprisespassing an electric current between an anode of alkali metal amalgam anda cathode immersed in a solution of alkali metal cyanide in liquidanhydrous ammonia and catalyzing the reaction between the ammonia andthe metal thus removed to yield the amide.

6. The rocess of manufacturing an alkali metal amide which comprisesbringing a solution of the alkali metal in liquid anhydrous ammoniacontainin a dissolved inert salt into contact with a solid catalystcapable of accelerating the reaction between the alkali metal and theammonia.

7 The recess of manufacturing an alkali metal amide which comprisesbringin a solution of the alkali metal in liquid alfiiydrous ammoniacontaining a dissolved alkali metal cyanide into contact with a solidcatalyst capable of accelerating the reaction between the alkali metaland the ammonia.

8. The process of manufacturing sodamide which comprises passing anelectric current between an anode of sodium amalgam and a cathodeimmersed in a solution of an inert sodium salt in liquid anhydrousammonia and catalyzing the reaction between the ammonia and the sodiumso removed to yield the amide.

9. The process of manufacturing sodamide which comprises bringing asolution of sodium in liquid anhydrous ammonia containing a dissolvedinert salt into contact with a solid catalyst capable of acceleratingthe reaction between the sodium and the ammonia.

10. The recess of manufacturing sodamide whic comprises bringing asolution of metallic sodium in liquid anhydrous ammonia into contactwith high-carbon steel. 11. The process of making alkali metal amidewhich comprises passing an electric current between an anode of alkalimetal amalgam and a cathode immersed in a solution of an inert alkalimetal salt in liquid anhydrous ammonia of such strength that two liquidlayers are formed, and catalyzing the reaction between the alkali metalremoved from the amalgam and the ammonia to yield the amide.

12. The process of making alkali metal amide which comprises passing anelectric current between an anode of alkali metal amalgam and a cathodeimmersed in a solution of an inert alkali metal salt in liquid anhydrousammonia of such strength that two liquid layers are formed andmaintaining a solid catalyst simultaneously into contact with bothlayers so that the alkali metal and ammonia react to form amide.

13. The process of making sodamide which comprises pasing an electriccurrent between a sodium amalgam anode and a cathode immersed in asolution of sodium cyanide in liquid anhydrous ammonia of such strengththat two liquid layers are formed, and causing the reaction between theammonia and the sodium removed from the anode to he catalyzed to yieldsodamide by contact with a surface of high-carbon steel.

14. The process of making sodamide which comprises electrolyzing anaqueous solution of a sodium salt with a mercury cathode to yield sodiumamalgam, removing sodium from said amal am by passing an electriccurrent from s'ai amalgam as anode to a cathode through a solution of aninert electrolyte in liquid anhydrous ammonia, and catalyzing thereaction between the sodium so removed and the ammonia to yield solidsodamide.

15. The process of making alkali metal amide which comprises removinalkali metal from an amalgam thereof an obtaining the amide from saidalkali metal by. catalytic acceleration of the reaction'between saidmetal and liquid anh drous ammonia without isolation of alkai metal.

16.'Apparatus for the manufacture of alkali metal amides comprising acell adapted to contain li uid anhydrous ammoma, means to supply a kalimetal amalgam thereto as anode, a cathode, electrical connections forsaid anode and cathode, a filter, means to pass a suspension of amidefrom the cell to the filter, and means to prevent loss of ammonia fromthe apparatus.

In witness whereof, I have hereunto sin ied my name this 13th day ofMarch 1 THOMAS EWAN.

